Research

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11 pages, 2131 KiB

Open AccessArticle

Enhanced Abrasion Resistance of Spark Plasma Sintered and HVOF Sprayed Hadfield High Manganese Steel by Turning and Diamond Smoothing

by Thomas Lindner, Hendrik Liborius, Bianca Preuß, Niclas Hanisch, Andreas Schubert and Thomas Lampke

J. Manuf. Mater. Process. 2022, 6(2), 48; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp6020048 - 17 Apr 2022

Cited by 2 | Viewed by 2685

Abstract

Austenitic high-manganese steels (HMnS) offer very high wear resistance under dynamic loading due to their high work hardening capacity. However, resistance to static abrasive loading is limited. Various approaches to increasing abrasion resistance are known from traditionally manufactured metallurgical components. These confirm the [...] Read more.

Austenitic high-manganese steels (HMnS) offer very high wear resistance under dynamic loading due to their high work hardening capacity. However, resistance to static abrasive loading is limited. Various approaches to increasing abrasion resistance are known from traditionally manufactured metallurgical components. These confirm the high potential for surface protection applications. In this work, the powder of the Hadfield HMnS X120Mn12 is prepared and processed by high-velocity oxy-fuel (HVOF) spraying and spark-plasma sintering (SPS). A good correlation was observed between the results of the HVOF and SPS specimen. Different surface conditions of the coatings and the sintered specimens were prepared by machining. Compared to the polished state, turning and diamond smoothing can increase the surface hardness from 220 HV to over 700 HV significantly. Regardless of the surface finish condition, similar good wear resistance can be demonstrated due to strong work hardening under sliding and reciprocating wear loading. In contrast, the finish machining process clearly influences abrasion resistance in the scratch test with the best results for the diamond smoothed condition. Especially against the background of current trends toward alternative coating systems, the presented results offer a promising approach for the development of HMnS in the field of coating technology. Full article

(This article belongs to the Special Issue Surface Integrity in Machining and Post-processing)

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13 pages, 3176 KiB

Open AccessArticle

Thermomechanical Impact of the Single-Lip Deep Hole Drilling on the Surface Integrity on the Example of Steel Components

by Jan Nickel, Nikolas Baak, Pascal Volke, Frank Walther and Dirk Biermann

J. Manuf. Mater. Process. 2021, 5(4), 120; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp5040120 - 09 Nov 2021

Cited by 7 | Viewed by 2469

Abstract

The fatigue behavior of components made of quenched and tempered steel alloys is of elementary importance, especially in the automotive industry. To a great extent, the components’ fatigue strength is influenced by the surface integrity properties. For machined components, the generated surface is [...] Read more.

The fatigue behavior of components made of quenched and tempered steel alloys is of elementary importance, especially in the automotive industry. To a great extent, the components’ fatigue strength is influenced by the surface integrity properties. For machined components, the generated surface is often exposed to the highest thermomechanical loads, potentially resulting in transformations of the subsurface microstructure and hardness as well as the residual stress state. While the measurement of the mechanical load using dynamometers is well established, in-process temperature measurements are challenging, especially for drilling processes due to the process kinematics and the difficult to access cutting zone. To access the impact of the thermomechanical load during the single-lip drilling process on the produced surface integrity, an in-process measurement was developed and applied for different cutting parameters. By using a two-color pyrometer for temperature measurements at the tool’s cutting edge in combination with a dynamometer for measuring the occurring force and torque, the influence of different cutting parameter variations on the thermomechanical impact on the bore surface are evaluated. By correlating force and temperature values with the resultant surface integrity, a range of process parameters can be determined in which the highest dynamic strength of the samples is expected. Thermally induced defects, such as the formation of white etching layers (WEL), can be avoided by the exact identification of critical parameter combinations whereas a mechanically induced microstructure refinement and the induction of residual compressive stresses in the subsurface zone is targeted. Further, eddy-current analysis as a non-destructive method for surface integrity evaluation is used for the characterization of the surface integrity properties. Full article

(This article belongs to the Special Issue Surface Integrity in Machining and Post-processing)

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20 pages, 6606 KiB

Open AccessArticle

Evaluation of Hardness and Residual Stress Changes of AISI 4140 Steel Due to Thermal Load during Surface Grinding

by Ewald Kohls, Carsten Heinzel and Marco Eich

J. Manuf. Mater. Process. 2021, 5(3), 73; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp5030073 - 05 Jul 2021

Cited by 6 | Viewed by 2872

Abstract

During surface grinding, internal material loads are generated, which take effect on the surface and subsurface zone of AISI 4140 steel. High thermal loads can result in specific material modifications, e.g., hardness reduction and tensile residual stresses, due to inappropriate combinations of system [...] Read more.

During surface grinding, internal material loads are generated, which take effect on the surface and subsurface zone of AISI 4140 steel. High thermal loads can result in specific material modifications, e.g., hardness reduction and tensile residual stresses, due to inappropriate combinations of system and process parameters which influence the functional performance of the ground component in a negative way. In order to avoid this damaging impact due to the thermal effect, an in-depth understanding of the thermal loads and the resulting modifications is required. This relationship is described in the concept of Process Signatures applied in this paper. Experimentally determined temperature-time histories at various depths below the surface were used to estimate the thermal loads at the surface and subsurface using a numerical approach based on the finite element method (FEM). The results show that the hardness change during surface grinding correlates with the maximum temperature rate at given maximum temperatures. In addition, correlations between the hardness change and the Hollomon–Jaffe parameter are identified, taking into account both the absolute temperature and its evolution over time. Furthermore, it was shown that the surface residual stresses correlate with the maximum local temperature gradients at the surface if no detectable tempering of the microstructure takes place. Full article

(This article belongs to the Special Issue Surface Integrity in Machining and Post-processing)

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11 pages, 2396 KiB

Open AccessArticle

Thermal Effects on Surface and Subsurface Modifications in Laser-Combined Deep Rolling

by Robert Zmich and Daniel Meyer

J. Manuf. Mater. Process. 2021, 5(2), 55; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp5020055 - 28 May 2021

Cited by 2 | Viewed by 1770

Abstract

Knowledge of the relationships between thermomechanical process loads and the resulting modifications in the surface layer enables targeted adjustments of the required surface integrity independent of the manufacturing process. In various processes with thermomechanical impact, thermal and mechanical loads act simultaneously and affect [...] Read more.

Knowledge of the relationships between thermomechanical process loads and the resulting modifications in the surface layer enables targeted adjustments of the required surface integrity independent of the manufacturing process. In various processes with thermomechanical impact, thermal and mechanical loads act simultaneously and affect each other. Thus, the effects on the modifications are interdependent. To gain a better understanding of the interactions of the two loads, it is necessary to vary thermal and mechanical loads independently. A new process of laser-combined deep rolling can fulfil exactly this requirement. The presented findings demonstrate that thermal loads can support the generation of residual compressive stresses to a certain extent. If the thermal loads are increased further, this has a negative effect on the surface layer and the residual stresses are shifted in the direction of tension. The results show the optimum range of thermal loads to further increase the compressive residual stresses in the surface layer and allow to gain a better understanding of the interactions between thermal and mechanical loads. Full article

(This article belongs to the Special Issue Surface Integrity in Machining and Post-processing)

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17 pages, 4921 KiB

Open AccessArticle

Surface Integrity Investigation to Determine Rough Milling Effects for Assessment of Machining Allowance for Subsequent Finish Milling of Alloy 718

by Jonas Holmberg, Anders Wretland, Johan Berglund, Tomas Beno and Anton Milesic Karlsson

J. Manuf. Mater. Process. 2021, 5(2), 48; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp5020048 - 13 May 2021

Cited by 3 | Viewed by 2530

Abstract

The planned material volume to be removed from a blank to create the final shape of a part is commonly referred to as allowance. Determination of machining allowance is essential and has a great impact on productivity. The objective of the present work [...] Read more.

The planned material volume to be removed from a blank to create the final shape of a part is commonly referred to as allowance. Determination of machining allowance is essential and has a great impact on productivity. The objective of the present work is to use a case study to investigate how a prior rough milling operation affects the finish machined surface and, after that, to use this knowledge to design a methodology for how to assess the machining allowance for subsequent milling operations based on residual stresses. Subsequent milling operations were performed to study the final surface integrity across a milled slot. This was done by rough ceramic milling followed by finish milling in seven subsequent steps. The results show that the up-, centre and down-milling induce different stresses and impact depths. Employing the developed methodology, the depth where the directional influence of the milling process diminishes has been shown to be a suitable minimum limit for the allowance. At this depth, the plastic flow causing severe deformation is not present anymore. It was shown that the centre of the milled slot has the deepest impact depth of 500 µm, up-milling caused an intermediate impact depth of 400 µm followed by down milling with an impact depth of 300 µm. With merged envelope profiles, it was shown that the effects from rough ceramic milling are gone after 3 finish milling passes, with a total depth of cut of 150 µm. Full article

(This article belongs to the Special Issue Surface Integrity in Machining and Post-processing)

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21 pages, 5530 KiB

Open AccessArticle

Simulation Study on Single-Lip Deep Hole Drilling Using Design of Experiments

by Daniel Fandiño, Vinzenz Guski, Robert Wegert, Hans-Christian Möhring and Siegfried Schmauder

J. Manuf. Mater. Process. 2021, 5(2), 44; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp5020044 - 04 May 2021

Cited by 4 | Viewed by 2767

Abstract

Single-lip deep hole drilling (SLD) is characterized by a high surface quality and compressive residual stress in the subsurface of the drill hole. These properties are strongly dependent on the cutting parameters of the SLD process and the actual geometry of the insert [...] Read more.

Single-lip deep hole drilling (SLD) is characterized by a high surface quality and compressive residual stress in the subsurface of the drill hole. These properties are strongly dependent on the cutting parameters of the SLD process and the actual geometry of the insert and the guide pads. In the present work, full 3D FE simulations of the SLD process were carried out to analyze the thermo-mechanical as-is state in the drilling contact zone by evaluating the feed force, the temperature, as well as the residual stress in the drill hole subsurface. An extensive simulation study was conducted on the effect of the process parameters on the properties using design of experiments (DoE). For the simulations, the Johnson–Cook (JC) constitutive law and the element elimination technique (EET) were applied to represent the material behavior of the workpiece, including chip formation. In-process measurements as well as results from the hole-drilling method to determine residual stresses were conducted to verify the numerical results. By means of DoE and analysis of variance (ANOVA), regression models were developed to describe the effect of the feed rate, cutting speed, and guide pad height on the temperature, feed force, and residual stress in the subsurface. Full article

(This article belongs to the Special Issue Surface Integrity in Machining and Post-processing)

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12 pages, 30284 KiB

Open AccessArticle

Influence of a Discontinuous Process Strategy on Microstructure and Microhardness in Drilling Inconel 718

by Tobias Wolf, Ivan Iovkov and Dirk Biermann

J. Manuf. Mater. Process. 2021, 5(2), 43; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp5020043 - 02 May 2021

Cited by 8 | Viewed by 2411

Abstract

Nickel-base alloys are proven materials in the fields of the aerospace and oil industry, which is due to their characteristic material properties of high temperature strength, high toughness and good oxidation resistance. These properties are beneficial to applications in technical components in general. [...] Read more.

Nickel-base alloys are proven materials in the fields of the aerospace and oil industry, which is due to their characteristic material properties of high temperature strength, high toughness and good oxidation resistance. These properties are beneficial to applications in technical components in general. However, they also represent challenges for machining. Especially while drilling Inconel 718, high temperatures occur in the chip-formation zone that implicate high thermal load in the material and thus, influence the surface integrity, for example, by causing white layers. Hence, the development of strategies to improve the ability to supply cutting edges with cooling lubricant is becoming increasingly important. In this context, an alternative process design, the discontinuous drilling, takes place, characterized by a periodic interruption of feed motion and thus, chip formation. A minor retraction movement from the contact zone enables the cooling lubricant to reach the cutting edges and to reduce their thermal load. In comparison to the conventional process of drilling Inconel 718, the effects of discontinuous drilling with varying numbers of interruptions on the resulting surface integrity and further parameters of drilling qualities are analyzed. Thereby, the prevention of process-related phase transformations due to thermal impact was discovered when a discontinuous drilling strategy was implemented. Full article

(This article belongs to the Special Issue Surface Integrity in Machining and Post-processing)

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11 pages, 3099 KiB

Open AccessArticle

Modeling of Drag Finishing—Influence of Abrasive Media Shape

by Irati Malkorra, Hanène Souli, Ferdinando Salvatore, Pedro Arrazola, Joel Rech, Mehmet Cici, Aude Mathis and Jason Rolet

J. Manuf. Mater. Process. 2021, 5(2), 41; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp5020041 - 26 Apr 2021

Cited by 4 | Viewed by 2743

Abstract

Drag finishing is a widely used superfinishing technique in the industry to polish parts under the action of abrasive media combined with an active surrounding liquid. However, the understanding of this process is not complete. It is known that pyramidal abrasive media are [...] Read more.

Drag finishing is a widely used superfinishing technique in the industry to polish parts under the action of abrasive media combined with an active surrounding liquid. However, the understanding of this process is not complete. It is known that pyramidal abrasive media are more prone to rapidly improving the surface roughness compared to spherical ones. Thus, this paper aims to model how the shape of abrasive media (spherical vs. pyramidal) influences the material removal mechanisms at the interface. An Arbitrary Lagrangian–Eulerian model of drag finishing is proposed with the purpose of estimating the mechanical loadings (normal stress, shear stress) induced by both abrasive media at the interface. The rheological behavior of both abrasive slurries (media and liquid) has been characterized by means of a Casagrande direct shear test. In parallel, experimental drag finishing tests were carried out with both media to quantify the drag forces. The correlation between the numerical and experimental drag forces highlights that the abrasive media with a pyramidal shape exhibits a higher shear resistance, and this is responsible for inducing higher mechanical loadings on the surfaces and, through this, for a faster decrease of the surface roughness. Full article

(This article belongs to the Special Issue Surface Integrity in Machining and Post-processing)

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17 pages, 48594 KiB

Open AccessEditor’s ChoiceReview

The Present State of Surface Conditioning in Cutting and Grinding

by Benedict Stampfer, Germán González, Michael Gerstenmeyer and Volker Schulze

J. Manuf. Mater. Process. 2021, 5(3), 92; https://0-doi-org.brum.beds.ac.uk/10.3390/jmmp5030092 - 20 Aug 2021

Cited by 17 | Viewed by 3078

Abstract

All manufacturing processes have an impact on the surface layer state of a component, which in turn significantly determines the properties of parts in service. Although these effects should certainly be exploited, knowledge on the conditioning of the surfaces during the final cutting [...] Read more.

All manufacturing processes have an impact on the surface layer state of a component, which in turn significantly determines the properties of parts in service. Although these effects should certainly be exploited, knowledge on the conditioning of the surfaces during the final cutting and abrasive process of metal components is still only extremely limited today. The key challenges in regard comprise the process-oriented acquisition of suitable measurement signals and their use in robust process control with regard to the surface layer conditions. By mastering these challenges, the present demands for sustainability in production on the one hand and the material requirements in terms of lightweight construction strength on the other hand can be successfully met. In this review article completely new surface conditioning approaches are presented, which originate from the Priority Program 2086 of the Deutsche Forschungsgemeinschaft (DFG). Full article

(This article belongs to the Special Issue Surface Integrity in Machining and Post-processing)

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